Process for electroless metallizing incorporating wear-resisting particles

ABSTRACT

There are disclosed processes for electroless metallizing workpieces to provide thereon a metal coating incorporating therein nonmetallic wear-resisting particles and the coated workpieces produced by such processes, the processes comprising contacting the workpieces with an electroless metallizing bath consisting of an aqueous solution of a metal salt and an electroless reducing agent therefor and a quantity of nonmetallic wear-resisting particles, wherein the particles are essentially insoluble in the plating bath and are noncatalytic and inert with respect thereto, the particles being present in the bath in an amount by weight no greater than about four times the weight of the metal in the bath expressed as free metal, and maintaining the particles in suspension throughout the bath during the metallizing of the workpiece; the electroless coating with the wear-resisting particles therein may be heat treated by heating to an elevated temperature in the range 100* C. to 600* C. for one hour or more further to harden the coating.

United States Patent Willy Metzger; Rudi Ott; Gunter Pappe; HelmutSchmidt, all of Solingen-Merscheid, Germany [72] Inventors [21] Appl.No. 698,129

[22] Filed Jan. 16, 1968 [45] Patented Nov. 2, 1971 [73] AssigneeGeneral American Transportation Corporation Chicago, 111.

[32] Priority Jan. 18, 1967 [33] Germany [54] PROCESS FOR ELECTROLESSMETALLIZING INCORPORATING WEAR-RESISTING PARTICLES 37 Claims, NoDrawings [52] US. Cl 117/130, 29/195,106/1,l17/160 [51 Int. Cl C23c 3/02[50] Field of Search 117/130,

[56] References Cited 3,326,700 6/1967 Zeblisky 117/130 X 3,378,4004/1968 Sickles 1 17/130 X FOREIGN PATENTS 1,041,753 9/1966 Great Britain[17/130 290,590 6/1965 Netherlands 204/41 OTHER REFERENCES Domnikov,Metal Finishing Feb. 1961 pp. 52- 54 l 17- 130 Primary Examiner-Ralph S.Kendall Attorney- Prangley, Clayton, Mullin, Dithmar and Vogel ABSTRACT:There are disclosed processes for electroless metallizing workpieces toprovide thereon a metal coating incorporating therein nonmetallicwear-resisting particles and the coated workpieces produced by suchprocesses, the processes comprising contacting the workpieces with anelectroless metallizing bath consisting of an aqueous solution of ametal salt and an electroless reducing agent therefor and a quantity ofnonmetallic wear-resisting particles, wherein the particles areessentially insoluble in the plating bath and are noncatalytic and inertwith respect thereto, the particles being present in the bath in anamount by weight no greater than about four times the weight of themetal in the bath expressed as free metal, and maintaining the particlesin suspension throughout the bath during the metallizing of theworkpiece; the electroless coating with the wear-resisting particlestherein may be heat treated by heating to an elevated temperature in therange 100 C. to 600 C. for one hour or more further to harden thecoating.

PROCESS FOR ELECTROLESS METALLIZING INCORPORATING WEAR-RESISTINGPARTICLES The present invention is directed to processes for electrolessmetallizing workpieces wherein the resultant metal coating hasincorporated therein wear-resisting particles.

It is an important object of the present invention to provide a processfor electroless metallizing a body to provide thereon a metal coatingincorporating therein wear-resisting particles so as to provide a highlywear-resistant coating on the body to protect such bodies that aresubject to wear by reason of sliding contact, rubbing contact, and thelike in use; the process comprising contacting the body with theelectroless metallizing bath consisting essentially of an aqueoussolution of the metal salt and an electroless reducing agent thereforand a quantity of wear-resisting particles, wherein the particles areessentially insoluble in the plating bath and are noncatalytic and inertwith respect thereto, the particles being present in the bath in anamount by weight no greater than about 4 times the weight of the metalin the bath expressed as free metal, and maintaining the particles insuspension throughout the bath during the metallizing of the body,thereby to produce on the surface of the body a coating of metal havingthe particles uniformly dispersed therethrough.

Another object of the invention is to provide a process of electrolessmetallizing of the type set forth wherein the wearresisting particleshave dimensions in the range 0.0l micron to I microns, a furtherpreferred range being from about 0.5 micron to about 25 microns, theparticles being maintained in suspension in the bath by mechanicalagitation in the bath or by passing the bath with the particles thereinacross the body, or by streams of minute bubbles of gases passingthrough the bath or by agitation of the body within the bath.

Still another object of the invention is to provide a process of thetype set forth and further comprising the step of heating the coating toan elevated temperature for a sufficient period of time to heat-hardenthe coating, a typical coating being heat-hardened by heating to atemperature in the range from about 100 C. to about 600 C. for about 1hour.

Still another object of the invention is to provide a process of thetype set forth which is particularly suited for applying wear-resistantcoatings to bodies formed of a material selected from the groupconsisting of aluminum, magnesium, copper, beryllium and their alloys,whereby additional heat-hardening of the coating is not required toprovide adequate wear-resistance in the coating.

Further features of the invention pertain to the particular arrangementof the steps of the processes and the compositions of the bath usedtherein and of the wear-resistant coatings produced thereby, whereby theabove-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification and to theseveral illustrative examples set forth therein.

in accordance with the present invention, there is provided a workpieceor article of manufacture having an outer surface that is to carry thedesired wear'resistant coating, the outer surface typically being onethat will be subject to sliding contact or rubbing contact with anothersurface, whereby to subject it to substantial wearing and bearingpressures. First, the workpiece is cleaned using one of severalwell-known cleaning methods, after which the workpiece is contacted withan electroless metallizing bath containing a quantity of wear-resistingparticles, the bath being for example a conventional chemical nickelplating bath of the nickel cation-hypophosphite anion type, and theparticles being essentially insoluble in the plating bath andnoncatalytic and inert with respect thereto and being present in thebath in an amount by weight no greater than about four times the weightof the metal in the bath expressed as free metal. During the platingprocess, the wear-resisting particles are maintained in suspensionthroughout the bath, whereby after a suitable time interval there isproduced on the surface of the workpiece a coating of the metal, such asnickel,

having uniformly dispersed therethrough a quantity of the wear-resistingparticles. Thereafter the workpiece may be subjected to a heat-hardeningstep in order to render the composite coating thus produced intimatelybonded thereto and of harder and more wear-resistant character.

The term wear-resistant coating" as used herein refers to a coating, theproperties of which changed in any manner whatsoever to increase thewear-resistant properties thereof; for example, the term includesincreasing the hardness of the coating by the incorporating thereinmaterials that are intrinsically harder than the coating itself; on theother hand, the term as used herein may include coatings wherein alubricating material, such as molybdenum disulfide, has been added tothe coating so that the lubricated surface of the coating wears longerdue to the lubricating properties thereof. Finally, it will beunderstood that the termwear-resistant coating" may also refer to acoating which embodies both particles which are intrinsically harderthan the coating and particles which add a lubricating property to thecoating.

While the processes of the present invention are fundamentallyindependent of the composition of the workpiece, ordinarily theworkpiece is formed of an industrial metal, such for example, as steel,although the workpiece may be formed of a nonmetallic material. In thelast mentioned instance, the workpiece is first subjected topretreatment in order to ac tivate the surface thereof so that it maysubsequently receive the electroless metallized coating that isinherently produced in the metallizing process. When the metallizingmetal is nickel, pretreatment may be that as disclosed in U.S. Pat. No.2,690,401, granted on Sept. 28, 1954 to Gregoire Gutzeit, William J.Crehan and Abraham Krieg, and in U. S. Pat. No. 2,690,402 granted onSept. 28, 1954 to William .I. Crehan.

The processes of the present application are particularly beneficial inproviding wear-resistant coatings on workpieces formed of materials,such as aluminum, magnesium, copper. or beryllium which are not readilyheat hardenable and which ordinarily are not heated after fabricationthereof, the inventive coating having wear-resistant properties suchthat additional treatment thereof is not necessary to provide asatisfactory wear-resistant surface.

it will be understood that a large number of metallizing processes ofthe electroless type may be utilized including electroless nickelprocesses, electroless cobalt processes and electroless copperprocesses. The invention is of particular applicability in the case ofelectroless nickel processes, specifically those using hypophosphiteanions as the electroless reducing agent. Furthermore, the electrolessmetallizing process in the case of electroless nickel is independent ofthe particular composition of the nickel plating bath of the nickelcation-hypophosphite anion type that is employed in the chemical nickelplating step, whereby a wide variety of these conventional chemicalnickel plating baths may be employed; which plating baths inherentlyproduce coatings essentially comprising by weight about percent to 97percent nickel and about 3 percent to 15 percent phosphorus.

The plating bath disclosed in U.S. Pat. No. 2,822,294, granted on Feb.4, 1958 to Gregoire Gutzeit, Paul Talmey and Warren G. Lee isparticularly recommended due to its simplicity and economy. Moreparticularly, this plating bath is of the nickel cation-hypophosphiteanion type, also containing lactic anion and having a pH in the acidrange 3.0 to A typical example of this chemical nickel plating bathuseful in the present invention has the following composition:

A quantity of the above plating bath-was placed in a plating vesselhaving a magnetic stirrer therein, after which there was added thereto 1percent by weight of the solids in the plating bath of 600 grit siliconcarbide particles, it being noted that the nickel content of the bath onthe solid basis expressed as nickel metal is about 0.5 percent. A steelworkpiece having a bearing surface thereon was then placed in theplating bath while the silicon carbide particles were maintained inagitated suspension throughout the plating bath, and while thetemperature of the plating bath was maintained in the general range 93C. to 98 C. After about an hour, there was present on the exposedsurfaces of the workpiece about one mil of a weanresistant coatingcomprising electroless nickel and a quantity of the silicon carbideparticles embedded in and distributed therethrough. The coating that isinherently produced by the particular plating bath essentially comprisesby weight about 86 percent nickel and about 9 percent phosphorus, andabout 5 percent silicon carbide.

The surface of the coated workpiece was rough and dull in appearance andhad a hardness in the nickel-phosphorus alloy area of 525 V.P.N.(Vickers Pyramid Number). The Taber Wear lndex (TWl) was determined andwas found to be 4.7. The Taber Wear Index is defined as the loss ofweight in mg. per 1000 revolutions of two CS-l rubber wheels under a1000 grams load, a TWI of representing a loss in thickness of about 0.01mil of coating. By contrast an electroless nickel coating made using thebath of example 1 without the addition of wear-resisting particlesthereto has a TWI of 15.2 whereby the coating of the present inventionincorporating therein the silicon carbide wear-resisting particlesmaterially imposes the wear-resistance of the coating, the improvementbeing essentially by a factor of3.

In the chemical nickel plating bath of example 1, the absoluteconcentration of hypophosphite in the bath expressed in mole/liter mayvary within the range from about 0.15 to about 1.20, and ratio betweenthe nickel cations and hypophosphite anions in the bath expressed inmolar concentrations may vary within the range from about 0.25 to about1.60. The lactic anion serves as a complexing agent and may be derivedfrom lactic acid or salts thereof, the absolute concentration of lacticions in the bath expressed in mole/liter being within the range fromabout 0.25 to about 0.60. The bath also includes an exalting additive,namely, the propionic anion, which has a concentration in the bathexpressed in mole/liter in the range from about 0.025 to about 0.060.Other exalting additives may be used in place of the propionic anion,the exalting additive being selected from the group consisting of simpleshort chain saturated aliphatic monocarboxylic acids, including three tofive carbon atoms and salts thereof. Further details of the compositionof the bath and the method of using the same are set forth in theaforementioned U.S. Pat. No. 2,822,294 and the disclosure thereof isincorporated herein by reference.

The silicon carbide particles useful in the process of example 1 mayhave a particle size in the range from about 0.5 micron to about 25microns, in order to obtain good suspension of the particles in theplating bath and in order to to obtain uniform distribution of theparticles in coating. Smaller particles inhibit the plating action, dueto close packing, while larger particles are kept dispersed in theplating bath only with extreme difficulty. The concentration of thesilicon carbon carbide particles in the plating bath should not exceedabout 4 times the weight of the nickel metal present in the bathexpressed as free metal, although smaller concentration of the siliconcarbide particles may be utilized, it being understood that the volumeof silicon carbide in the coating will be a function of theconcentration of the silicon carbide particles in the plating bath aswell as the effectiveness of the dispersion thereof. In example 1, thesilicon carbide comprises about percent by volume of the wear-resistantcoating, although it will be understood that the volume of the siliconcarbide particles may vary from as little as 1 percent up to as much as40 percent ofthe volume ofthe coating.

Other thicknesses of the coating may be provided, and the coating mayhave a thickness in the range from about 5 microns to about 200 micronsor more if desired.

Summarizing, with respect to example 1 above, there is provided aprocess of electroless" plating of a nickel-phosphorus alloy coating ona workpiece, the coating containing silicon carbide particlesdistributed therethrough and being a relatively thick dispersionhardened" metal deposit. The expression electroless plating as usedherein refers to the plating of metal coatings without the applicationof an external electrical current, and preferably by a chemicalreduction of the electroless metal utilizing an electroless reducingagent for the metal, thereby to accomplish a process of electrolessmetallizing. The term dispersion hardened as used herein refers to thedescribed metal coatings in which are embedded inert solid particlesduring the laying down of the metal coating, the particles beingpartially or completely embedded in and held in position by the coating.

The lead content of the nickel plating bath of example 1 performs theimportant function of stabilizing the bath during the plating operation.It will be understood that other types of stabilizers and other amountsof stabilizers may be advantageously utilized in connection with thepresent invention, suitable such stabilizers being disclosed in U.S.Pat. No. 2,762,723 granted Sept. 11, 1958 to Paul Talmey and GregoireGutzeit, the disclosure of that patent being incorporated herein byreference.

Alkaline nickel plating baths may be utilized advantageously in thepresent invention, and particularly when coating certain plastics andcertain metals such as magnesium, examples of suitable alkaline bathsbeing set forth in U.S. Pat. No. 3,21 1,578 granted Oct. 12, 1965 toGregoire Gutzeit, the disclosure thereof being incorporated herein byreference.

In general any nonmetallic particle may be utilized as a wear-resistingparticle in the process of example 1, it simply being necessary that theparticles be essentially insoluble in the plating bath and that theparticles be noncatalytic and inert with respect to the reducing of themetal salt by the electroless reducing agent therefor. In thisconnection it is pointed out that a wide variety of such nonmetallicwear-resisting particles may be used, and more specifically, there maybe used the following: kaolin; glass flour, talc, synthetic organicplastic resin powders; and oxides, carbides, nitrides, borides,silicides, sulfides, silicates, sulfates, carbonates, phosphates,oxalates or fluorides of aluminum, boron, chromium, hafnium, molybdenum,silicon, titanium, tantalum, vanadium, tungsten, zirconium, nickel,magnesium calcium, barium, strontium, cerium, iron or manganese. Theparticle size of the wear-resisting particles may be of the order of0.01 micron to microns, a preferred size being in the range from about0.5 micron to about 25 microns.

Furthermore, the particles must be essentially insoluble in the platingbath, i.e., must have a very low solubility therein on the order of nomore than about 0.01 mole per liter. In addition, the wear-resistingparticles must be noncatalytic and inert with respect to the reducingagent and the reaction of the reducing agent with the coating metal inthe bath, and also the particles must not interfere with or stop theplating reaction. The concentration of the wear-resisting particles inthe plating bath is preferably in the range from about 0.1 percent byweight of the solids to about 2 percent by weight of the solids, but inany event not more than 4 times the weight of the electroless platingmetal in the bath when the weight of the metal is expressed as the freeor reduced metal. in certain instances it may be desirable to provide anacid or solvent wash to the particles before the addition thereof to theplating bath, thereby to avoid contamination and to increase thestability of the plating bath.

Other suitable methods of maintaining the wear-resisting particles insuspension may be used in addition to that described above with respectto example 1. For example, a mixture of the plating solution and thewear-resisting particles may be advantageously pumped through the bottomof the plating vessel, the bottom of the plating vessel being dishshapedand symmetrical, whereby a unifonn stream of the plating bath with thewear-resisting particle suspended and entrained therein is passed orflooded across the surfaces of the workpiece being coated.

Another advantageous system for maintaining the wear-resisting particlesin suspension is to provide a symmetrical plating bath having dispersedin the bottom thereof a spider including a number of very small gasoutlets therein. In this manner very fine air bubbles can be introducedinto the plating bath via the spider, the air bubbles serving to holdthe wear-resisting particles in suspension throughout the platingsolution. Other gases such as nitrogen, or one of the noble gases, maybe used in place of air.

Yet another method of maintaining the wear-resisting particles insuspension is to agitate and move the workpiece within the platingsolution, such movement of the workpiece causing currents in the platingsolution which tend to hold the wear-resisting particles in suspension.Each of the above-mentioned alternative methods of maintaining thewear-resisting particles in suspension has been successfully utilized inconjunction with the process of example 1 above.

It will be appreciated that the process of example I is particularlyuseful when applied to workpieces having surfaces that are to beemployed in sliding applications, such as slide bearings, motorhousings, shafts, and the like. It will be understood, however, that theincorporation of the wear-resisting particles in the electrolessdeposited metal coating affects other properties of the coating inaddition to the hardnessand wear-resistance thereof. In general thephysical, chemical and electrochemical properties of the coating areaffected including the coefficient of friction, the temperaturestability of the coating, the oxidation stability of the coating, thecorrosion stability of the coating, the reflectivity and/or glossthereof, etc.

Turning now to a consideration of the electroless chemical nickelplating baths useful in the present invention, there are a number ofsuitable available compositions, such for example, as disclosed in U.S.Pat. No. 2,532,283, granted on Dec. 5, 1950 to Abner Brenner and GraceE. Riddell, U.S. Pat. No. 2,658,84l, granted on Nov. 10, 1953 toGregoire Gutzeit and Abraham Krieg, or U.S. Pat. No. 2,658,842 grantedon Nov. I0, 1953 to Gregoire Gutzeit and Ernest J. Ramirez.

The following are additional examples of such baths useful in thepresent invention.

EXAMPLE 2 Nickel chloride 30 g./l. Sodium acetate l3 3.1!. Sodiumhypophosphite l gJl. pH 4 Temperature 95 C.

EXAMPLE 3 Nickel sulfate 30 g-ll. Sodium citrate I00 3.". Ammoniumchloride 50 g./l. Sodium hypophosphite l0 gJl. pH 8-l0 Temperature 95'C.

The plating process of example 1 was repeated utilizing the bath of theabove composition, there being produced on the workpiece an electrolessnickel coating having the silicon carbide particles uniforrnly dispersedtherethrough, the coating possessing the valuable properties describedwith respect to example I.

The hardness of the electroless nickel coatingsincorporating therein thesilicon carbide particles as described in conjunction with examples 1 to3 above can be further hardened and rendered even more wear-resistant bya heat treatment of the coating after deposition thereof. There isdisclosed in U.S. Pat. No. 2,908,419, granted on Oct. 13, 1959 to PaulTalmey and William J. Crehan a suitable heat treatment process toincrease the hardness of such electroless nickel coatings, and thedisclosure of that patent is incorporated herein by reference. Theelectroless nickel portion of the coatings of examples l to 3 maycontain from about percent to about 97 percent nickel and from about 3percent to about lS-percent phosphorus by weight, certain of the bathssuch as that of example actually providing compositions in the rangefrom 88 percent to 94 percent nickel and from about 6 percent to about12 percent phosphorus by weight. The electroless nickel coating morespecifically after heat treatment constitutes a stable solidcharacterized by the presence of substantial microcrystals of nickelphosphide dispersed in a matrix of nickel metal and having a resultanthardness as high as 1200 V.P.N. the hardness varying down to about 575V.P.N. depending upon the heating temperature and time.

The following is an example of the heat treatment of the novel coatingof example 1.

EXAMPLE 4 A workpiece having a coating thereon produced as in example lwas gradually heated in an oven from C. to 400 C. for a period of 1hour. At the end of the hour it was found that the hardness of theelectroless nickel portion of the coating was 1,081 V.P.N. and thewear-resistance was 1.9 TWl. This compared with a TWl of 4.2 for theelectroless nickel coating alone without the addition of thewear-resisting particles thereto.

It will be appreciated that the coatings of examples 2 and 3 above canbe likewise heat-hardened by processing in accordance with example 4herein, and further as explained in the U.S. Pat. No. 2,908,419 referredto above.

It has been found that sulfides are also useful as wear-resistingparticles in the present invention, the following being examples of theuse of molybdenum sulfide particles as the wearresisting particles.

EXAMPLE 5 The plating bath and the coating process of example l wereduplicated but the plating bath had disposed therein 1 percent weight ofthe dry solids of granulated molybdenum disulfide having an averageparticle size of about 50 microns. There resulted from one hour ofplating a coating having a thickness of 0.78 mil and possessing a roughtexture. The hardness of the electroless nickel coating was 508 V.P.N.and the wear-resistance thereof was 4.9 TWl. The coated workpiece madein accordance with example 5 had good lubricating properties impartedthereto by the molybdenum disulfide and possessed the other advantagesand properties as described above with respect to example 4.

The coating of example 5 may also be heat-hardened, an example of such aprocess being as follows:

EXAMPLE 6 workpiece with the coating of example 5 thereon was furtherprocessed and heat treated as in example 4 above to provide aheat-hardened coating having a hardness of l0l8 V.P.N. and a wearresistance of l l TWl.

Metal oxides are examples of other wear-resisting particles which areuseful in carrying out the processes of the present invention. Thefollowing is an example utilizing aluminum oxide particles:

EXAMPLE 7 The plating bath and process of example I was utilized butthere was substituted for the silicon carbide particles aluminum oxideparticles having a size of about 0.5 micron, and having a concentrationby weight of about 1 percent of the dry solids in the plating bath.There was produced a bright coating of electroless nickel havingdispersed therethrough the aluminum oxide particles, 0.6 mil of thecoating being produced in one hours time. The hardness of the coating inthe nickel area was 572 V.P.M. and the wear-resistance thereof was 9.8TWl. The wear-resistant coating made in accordance with example 7 hadthe other desirable properties of the coating produced by the process ofexample I as set forth above.

The process of example 7 was repeated utilizing a concentration of thealuminum oxide particles of 0.1 percent by weight on a dry basis of thesolids in the plating bath. There resulted after one hour of plating acoating having a thickness of 0.6 mil and a hardness of 627 V.P.N. Inanother process in accordance with example 7, the aluminum oxideparticles were present in the plating bath in a concentration of 2percent by weight on a dry basis of the solids, there resulting a roughcoating having a thickness of 0.43 mil and a hardness of 642 V.P.N. Inyet another variation of the process of example 7, the aluminum oxideparticles utilized had a size of 0.05 micron and a concentration of lpercent in the bath, thereby to produce after one hour a bright coatinghaving a thickness of0.67 mil and a hardness of6l2 V.P.N.

Finally, there was carried out a variation of the process of example 7,wherein the aluminum oxide particles had a size of I micron and werepresent in a concentration of 1 percent in the bath, there resultingafter 1 hour of plating a rough coating having a thickness ofO.52 miland a hardness of572 V.P.N.

The coatings made in accordance with example 7 may also be heat-treatedto improve the wear-resistant properties thereof, the following being anexample of such a process.

EXAMPLE 8 A workpiece coated in accordance with the process of example 7was heat-treated in accordance with the process of example 4, theresultant coating having a hardness of 1049 V.P.N. and a wear-resistanceof 4.6 TWl.

A wide variety of metal oxides may be utilized in the place of aluminumoxide in examples 7 and 8, and more specifically, titanium oxides may beutilized to provide a dull rough coating having a thickness of 0.54 milafter I hour of plating and a hardness of 572 V.P.N. Tin oxide powdersubstituted for the aluminum oxide in example 7 provided after 1 hour abright coating having a thickness of 0.59 mil and a hardness of 536V.P.N. While chromium oxide when substituted in example 7 in the form ofa liquid containing particles of 0.5 micron size after 1 hour produced adull smooth coating having a thickness of0.69 mil and a hardness of 525V.P.N.

Silicas having a small particle size comprise another class of materialsthat are particularly useful as wear-resisting particles in theprocesses of the present invention, examples of which are a follows:

EXAMPLE 9 The process of example I was repeated using the bath thereofbut substituting silica as the wear-resisting particles therein, thesilica utilized being that sold under the trade designation Syloid 244"and having a particle size in range lmicrons. After 1 hour ofplatingwith a 1 percent concentration of the silica in the bath on a dry weightbasis, there was produced a bright coating having a thickness of 0.76mil, a hardness of 525 V.P.N. and a wear-resistance of 14.6 TWl.Comparable results were obtained utilizing other synthetic silicasincluding that sold under the trade designation "Syloid 266 and thatsold under the trade designation QUSO 6-30 The coating of example 10 canbe further hardened by heat treatment thereof and the following is asexample:

EXAMPLE l0 A workpiece carrying a coating made in accordance withexample 9 was heat treated in accordance with example 4, and

plication of a wear-resistant coating to an aluminum workpiece:

EXAMPLE 1 l The plating bath of example 1 was modified by adding thereto0.5 grams per liter of potassium fluoride dihydrate, the preferredconcentration being in the range from about 0.001 to about 0.04mol./liter. An aluminum workpiece was then coated in accordance with theprocess of example I to provide thereon a rough dull coating having athickness after I hour of plating of 0.54 mil, a hardness of 508 V.P.N.and a wear-resistance of 4.5 TWl. It will be appreciated that thisworkpiece has a bearing surface provided by the coating that ismaterially more wear-resistant than either the aluminum metal or theelectroless nickel plate without the addition of the silicon carbideparticles thereto.

ln certain instances, it is possible to heat treat aluminum baseworkpieces, the following being an example of such a heat treatment:

EXAMPLE l2 The aluminum workpiece of example I l was heated to l75 C.for l hour to provide a heat-hardening of the coating thereon. Morespecifically, the coating now had a hardness of 724 V.P.N. and awear-resistance of 3.2 even afier this mild heat treatment of theworkpiece.

As noted above, the workpiece of examples 1 l and I2 are rough and dullin appearance. It has been found that if the surface of the coating ofexam ple l l, i.c., without heat-treatment, is honed or lapped to renderthe surface smooth, the wear-resistance thereof is improved and morespecifically the TWl is decreased to about 2.2.

Other carbides are useful as wear-resisting particles when applied toaluminum base workpieces, the following being an example thereof:

EXAMPLE 13 The process of example 11 was repeated, but there wassubstituted for the silicon carbide particles therein tungsten carbideparticles having a size of 400 mesh maximum, the tungsten carbide beingthat sold under the trade designation Haynes Alloy No. 956." Thetungsten carbide particles were utilized in a concentration of 1 percentof the dry solids in the bath, and after l hour of plating, there wasprovided a rough coating having a thickness of 0.45 mil, a hardness of593 V.P.N., and a wear-resistance of 6.6 WI.

The coating of example 13 can also be further hardened by heat treatmentthereof, the following being an example:

EXAMPLE l4 The aluminum workpiece with the coating of example l3 thereonwas heat treated by being heated to a temperature of 270 C. for 16hours. The heat treated coating was found to have a hardness of l,l45V.P.N. and a wear-resistance of 2.1 TWl.

Certain metal sulfides may also advantageously be incorporated inelectroless nickel plating applied to aluminum base alloys, thefollowing being an example thereof:

2. EXAMPLE 15 The process of example 5 was repeated by substituting analuminum base workpiece for the steel workpiece thereof, whereby therewas provided after l hour of plating a rough coating having a thicknessof 0.78 mil, a hardness of 606 V.P.N. and a wear-resistance of 2.7.

The workpiece of example l5 if heat treated can have the hardness of thecoating thereon increased, the following being an example:

EXAMPLE [6 The aluminum base workpiece carrying the coating of examplel5 was heated to 270 C. for a period of 8 hours to provide aheat-hardened coating having a hardness of 927 V.P.N. and awear-resistance of 1.5 TWl.

In the above examples, metallizing baths have been illustrated whereinnickel cations have been chemically reduced by hypophosphite anions. Itwill be understood that other electroless reducing agents may beutilized, the following being an example thereof:

EXAMPLE I? There was provided an electroless nickel plating bath havingthe following composition and characteristics:

Nickel chloride 30 g.ll. Sodium citrate l g./l. Sodium acetate 20 g./l.Sodium succinate 20 g./l. N-diethylborazane 30 ml.ll. Lead chloride 0.0lg./l. Methanol 50 ml./l. pH 6 Temperature 65 C.

A quantity of silicon carbide particles was added to the above platingbath with a concentration of 1 percent of the dry ingredients in thebath, the silicon carbide having a size of grit 600. A steel workpiecewas immersed in the plating bath and the particles were held insuspension by stirring of the bath. After 1 hour, there was provided acoating of electroless coating on the workpiece, the coating havingdispersed therein silicon carbide particles. The coating had all of theuseful characteristics and advantages described above with respect tothe coating produced by the process of example 1.

Other borazane reducing agents may be used in place of that set forth inexample 17 above. In general, any aklkyl borazane may be used, anotherpreferred reducing agent being dimethyl-borazane. Also useful is sodiumborahydride.

The present invention is also applicable to processes wherein othermetals are plated by electroless plating, the following being examplesof the plating of cobalt coatings on steel workpieces and incorporatingin the coatings wcar-resisting particles, all in accordance with thepresent invention.

EXAMPLE 18 There was formulated an electroless cobalt plating solutionhaving the following composition and characteristics:

Cobalt chlorideas 1. Sodium acetate 20 g./l. Sodium hypophosphite l0g-ll. pH 4.5 Temperature 95" C.

There was added to this solution 1 percent by weight of the dryingredients thereof of silicon carbon particles having the size of 600grit. After 1 hour of plating during which the solution was thoroughlyagitated uniformly to suspend the silicon carbide particles, there wasproduced on the surface of the workpiece an electroless cobalt coatinghaving uniformly dispersed therethrough silicon carbide particles. Theresultant coating had the desirable characteristics described above withrespect to the coating produced by the process of example l.

it, EXAMPLE 19 A plating solution having the following composition andcharacteristics was fonnulated:

Cobalt sulfate 30 gJl. Sodium citrate l l0 5.". Ammonium chloride 45g./l. Sodium hypophosphitc l2 gJl. pH 9 Temperature C.

There was added to the plating solution silicon carbide particles in aconcentration of 1 percent of the dry ingredients of this platingsolution, the particles having the size of 600 grit. A steel workpiecewas placed in the plating solution and the solution was vigorouslystirred to suspend the silicon carbide particles uniformly therethrough;after an hour, there was produced on the surface of the workpiece acoating of electroless cobalt having silicon carbide particles uniformlydispersed therethrough. The coating had all of the desirablecharacteristics and advantages of the coating of the process of example1, described above.

Two electroless metals may be codeposited from an electroless platingsolution as is known in the art and such plating solutions are useful incarrying out the process of the present invention, the following beingexamples thereof:

EXAMPLE 20 An electroless plating solution was formulated having thefollowing composition and characteristics:

Nickel chloride 20 Cobalt chloride l0 g.ll. Sodium citrate 20 g./l.Sodium hypopltosphite l0 gJl. pH 4.2 Temperature 95C.

To the plating solution there was added silicon carbide particles in aconcentration of 1 percent of the dry ingredients by weight, theparticles having the size of 600 grit. A steel workpiece was immersed inthe plating solution while the plating solution was vigorously stirredso as uniformly to suspend the silicon carbide particles throughout thevolume thereof. After an hour of plating, there was provided on theworkpiece a nickel-cobalt coating having uniformly dispersedtherethrough silicon carbide particles. The resultant coating had theseveral desirable properties and characteristics discussed above withrespect to the coating produced by the process of example 1.

EXAMPLE 21 An electroless plating solution was formulated having thefollowing composition and characteristics:

Nickel sulfate 25 gJl. Cobalt chloride 5 g.Il. Ammonium chloride 60 gJl.Sodium hypophosphite l5 g./l. pH 9.5 Temperature 95' C.

To this plating solution was added silicon carbide particles in aconcentration of 1 percent by weight of the dry ingredients therein, theparticles having a size of 600 grit. A steel workpiece was immersed inthe plating solution while the solution was vigorously agitated tomaintain the silicon carbide particles in suspension throughout thesolution during the coating of the workpiece. After an hour, theworkpiece had thereon a nickel-cobalt coating having silicon carbideparticles uniformly dispersed therethrough. The coating waswear-resistant and had the desirable properties and characteristicsdiscussed above with respect to the coating produced by the process ofexample I.

It will be understood that the hardness and wear-resistance of thecoatings of examples I? through 2l can be improved by heat treatmentthereof, i.e., by the heating thereof to an elevated temperature for asufficient period of time to effect a heat-hardening thereof.

An electroless plating bath was formulated having the followingcomposition and characteristics:

Copper sulfate 20 g.Il. Triethanolamine I g./l. Formaldehyde solutionml.ll. pH l2.5 Temperature C.

There was added to the electroless plating solution silicon carbideparticles in a concentration of 1 percent by weight of the dryingredients in the solution, the silicon carbide particles having a sizeof 600 grit. A steel workpiece was immersed in the plating solution andthe solution was vigorously agitated to maintain the silicon carbideparticles in suspension throughout the solution during the coating ofthe workpiece, After an hour, the workpiece had an appreciable coatingthereon of copper having dispersed uniformly therethrough siliconcarbide particles. The resultant coating had the hardness andwear-resistance and other desirable properties and characteristicsdiscussed above with respect to the coating provided by the process ofexample 1.

The following are yet other examples of workpieces which may besuccessfully coated utilizing the present invention, the chemicalcomposition being other than the steel and aluminum given in the abovespecific examples.

EXAMPLE 23 The process of example 1 was repeated using a workpiececonsisting of copper with essentially the same results in regard to thewear-resistance of the coating obtained.

EXAMPLE 24 The process of example 1 was repeated using a workpiececonsisting of brass with essentially the same results in regard to thewear-resistance of the coating obtained.

EXAMPLE 25 Example 25 The process of example I was repeated using aworkpiece consisting of beryllium alloy with essentially the sameresults in regard to the wear-resistance of the coating obtained.

Example 26 The process of example I was repeated using a workpiececonsisting of nickel with essentially the same results in regard to thewear-resistance of the coating obtained.

EXAMPLE 27 The process of example l7 was repeated using a workpiece ofmagnesium. The coating had all of the characteristics described abovewith respect to the wear-resistance of the coating of example 17.

Yet other wear-resisting particles may be utilized advantageously in thepresent invention as follows:

EXAMPLE 28 The electroless plating bath of example 1 was utilized in theprocess of example 1, but I percent by weight on the dry basis of boronnitride was substituted for the silicon carbide therein. The coatingobtained after one hour of plating had much improved wear-resistance duefundamentally to the lubricating properties of the boron nitrideparticles.

EXAMPLE 29 The plating solution and the process of example I wererepeated but there was substituted for the silicon carbide therein 1percent by weight of M icrothene F N-5l0," a polyethylene resin powderhaving a particle size in the range less than 30 microns. There wasobtained an electroless metal coating which had improved wear-resistancedue to the incorporation of the plastic particles therein.

It will be understood that the wear-resisting properties of the coatingsmade in accordance with the present invention may be derived from boththe incorporation of hard particles therein and the incorporation oflubricating particles therein. The following is an example of such aprocess and coating derived therefrom.

EXAMPLE 30 The plating bath and the process of example 1 were utilizedbut there was in addition added thereto 1 percent by weight on a drybasis of molybdenum disulfide having a particle size of about 50microns. The resultant coating had much improved wear-resistance, thewear-resistance being imparted thereto both by the hard silicon carbideparticles and the lubricating molybdenum disulfide particles.

From the above, it will be seen that there have been provided processesfor electroless metallizing of workpieces to provide thereon metalcoatings incorporating therein wear-resisting particles, which processesfulfill all of the objects and advantages set forth above. In addition,the processes provide coated workpieces with the improved coatingsthereon, all in accordance with the objects set forth above.

While there have been described what are at present considered to becertain preferred embodiments of the invention, it'will be understoodthat various modifications may be made therein, and it is intended tocover in the appended claims all such modifications as fall within thetrue spirit and scope of the invention.

What is claimed is:

l. A process of electroless metallizing a body to provide on the surfacethereof a metal coating incorporating therein weanresisting particles,which process comprises contacting the surface of said body with astable electroless metallizing bath consisting essentially of an aqueoussolution of a metal salt and an electroless reducing agent therefor anda stabilizer for said bath and a quantity of wear-resisting particles,wherein said particles are nonmetallic and essentially insoluble in theplating bath and are noncatalytic and inert with respect thereto; saidparticles being present in said bath in an amount by weight in the rangefrom about 0.1 percent to about 2 percent of the solids in said bath andno greater than about 4 times the weight of the metal in said bathexpressed as free metal, and maintaining said particles in suspensionthroughout said bath during the metallizing of said body for a timesufficient to produce a coating having a thickness of at least about 5microns, thereby to produce on the surface of said body a coating of themetal having said particles uniformly dispersed therethrough.

2. The process of electroless metallizing set forth in claim I, whereinsaid wear-resisting particles are silicon carbide particles.

3. The process of electroless metallizing set forth in claim I, whereinsaid wear-resisting particles are tungsten carbide particles.

4. The process of electroless metallizing set forth in claim I, whereinsaid wear-resisting particles are molybdenum sulfide particles.

5. The process of electroless metallizing set forth in claim I. whereinsaid wear-resisting particles are silica particles.

6. The process of electroless metallizing set forth in claim I, whereinsaid wear-resisting particles are aluminum oxide articles.

7. The process of electroless metallizing set forth in claim I, whereinsaid wear-resisting particles have dimensions in the range from about0.0] micron to about I00 microns.

8. The process of electroless metallizing set forth in claim I, whereinsaid wear-resisting particles have dimensions in the range from about0.5 micron to about 25 microns.

9. The process of electroless metallizing set forth in claim I, whereinsaid particles are maintained in suspension throughout said bath bymechanically agitating said bath and said particles.

10. The process of electroless metallizing set forth in claim 1, whereinsaid particles are maintained in suspension throughout said bath bypassing said bath with said' particles therein past said body.

4. The process of electroless metallizing set forth in claim 1, whereinsaid particles are maintained in suspension by streams of minute bubblesof gases passing through said bath.

12. The process of electroless metallizing set forth in claim ll,wherein said particles are maintained in suspension throughout said bathby agitation of said body within said bath.

13. The process of electroless metallizing set forth in claim 1, andfurther comprising the step of heating said coating to an elevatedtemperature for a sufficient period of time to heatharden said coating.

14. A process for coating the surface of a body with a nickel coatingincorporating therein wear-resisting particles, which process comprisescontacting the surface of said body with a stable bath consistingessentially of an aqueous solution of nickel salt and a reducing agenttherefor and a stabilizer for said bath and a quantity of wear-resistingparticles, wherein said particles are nonmetallic and essentiallyinsoluble in the plating bath and are noncatalytic and inert withrespect thereto, said particles being present in said bath in an amountby weight in the range from about 0.l percent to about 2 percent of thesolids in said bath and no greater than about 4 times the weight ofnickel in said bath expressed as nickel metal, and maintaining saidparticles in suspension throughout said bath during the coating of saidbody for a time sufficient to produce a coating having a thickness of atleast about 5 microns, thereby to produce on the surface of said body acoating of nickel having said particles uniformly dispersedtherethrough.

E5. The process of coating set forth in claim 14, wherein said reducingagent is a hypophosphite.

116. The process of coating set forth in claim 15, wherein the absoluteconcentration of hypophosphite in said bath expressed in mole/liter iswithin the range 0.l5 to 1.20, and the ratio between nickel andhypophosphite in said bath expressed in molar concentrations is withinthe range 0.25 to 1.60.

17. The process of coating set forth in claim 15, wherein said bath alsoincludes a complexing agent selected from the group consisting of lacticacid and slats thereof.

18. The process of coating set forth in claim 17, wherein the absoluteconcentration of lactic ions in said bath expressed mole/liter is withinthe range 0.25 to 0.60.

19. The process of coating set forth in claim 15, wherein said bath alsoincludes an exalting additive selected from the group consisting ofsimple short chain saturated aliphatic monocarboxylic acids includingthree to five carbon atoms and salts thereof.

20. The process of coating set forth in claim 19, wherein the absoluteconcentration of said exalting additive in said bath expressed inmole/liter is within the range 0.025 to 0.060.

21. The process of coating set forth in claim 15, wherein said bath alsoincludes a complexing agent selected from the group consisting of lacticacid and slats thereof, and an exalting additive selected from the groupconsisting of simple short chain saturated aliphatic monocarboxylicacids including three to five carbon atoms and salts thereof.

22. The process of coating set forth in claim 21, wherein the absoluteconcentration of lactic ions in said bath expressed in mole/liter iswithin the range 0.25 to 0.06, and the absolute concentration of saidexalting additive in said bath expressed in mole/liter is within therange 0.025 to 0.060.

23. The process of coating set forth in claim 15, and further comprisingthe step of heating said coating to an elevated temperature for asufficient period of time to heat-harden said coating.

2d. The process of coating set forth in claim 23, wherein the coating isheated to a temperature in the approximate range C. to 600 C. throughouta time interval of at least about l hour.

25. The process of coating set forth in claim 14, wherein said reducingagent is an alkyl-borazane.

26. A process of applying a nickel coating incorporating thereinwear-resisting particles to the surface of a body essentially formed ofa material selected from the group consisting of aluminum and itsalloys, which process comprises contacting the surface of said body witha stable bath consisting essentially of an aqueous solution of a nickelsalt and a hypophosphite and a stabilizer for said bath and a quantityof wear-resisting particles and wherein said particles are nonmetallicand essentially insoluble in the plating bath and are noncatalytic andinert with respect to the reduction of the nickel salt by thehypophosphite, said particles being present in said bath in an amount byweight in the range from about 0.! percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofnickel in said bath expressed as nickel metal, and maintaining saidparticles in suspension throughout said bath during the metallizing ofsaid body for a time sufiicient to produce a coating having a thicknessof at least about 5 microns thereby to produce on the surface of saidbody a coating of nickel having said particles uniformly dispersedtherethrough.

27. The process of coating as set forth in claim 26, wherein said bathadditionally consists essentially of a fluoride, wherein the absoluteconcentration of fluoride anions in said bath expressed in mole/liter isin the range from about 0.001 to about 0.04.

28. A process of applying a nickel coating incorporating thereinwear-resisting particles to the surface of a body essentially formed ofa material selected from the group consisting of magnesium and itsalloys, which process comprises contacting the surface of said body witha stable bath consisting essentially of an aqueous solution of a nickelsalt and a hypophosphite and a stabilizer for said bath and a quantityof wear-resisting particles, and wherein said particles are nonmetallicand essentially insoluble in the plating bath and are noncatalytic andinert with respect to the reduction of the nickel salt by thehypophosphite, said particles being present in said bath in an amount byweight in the range from about 0.1 percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofnickel in said bath expressed as nickel metal, and maintaining saidparticles in suspension throughout said bath during the metallizing ofsaid body, for a time sufficient to produce a coating having a thicknessof at least about 5 microns, thereby to produce on the surface of saidbody a coating of nickel having said particles uniformly dispersedtherethrough.

29. A process of applying a nickel coating incorporating thereinwear-resisting particles to the surface of a body essentially formed ofa material selected from the group consisting of beryllium and itsalloys, which process comprises contacting the surface of said body witha stable bath consisting essentially of an aqueous solution of a nickelsalt and a hypophosphite and a stabilizer for said bath and a quantityof wear-resisting particles, and wherein said particles are nonmetallicand being present in said bath in an amount by weight in the range fromabout 0.1 percent to about 2 percent of the solids in said bath and nogreater than about 4 times the combined weight of the nickel and thecobalt in said bath expressed as nickel metal and cobalt metal, andmaintaining said particles in suspension throughout said bath during hecoating of said body for a time sufficient to produce a coating having athickness of at least about 5 microns, whereby to produce on the surfaceof said body a coating of a nickel-cobalt alloy having said particlesuniformly dispersed therethrough.

30. A process of applying a nickel coating incorporating thereinwear-resisting particles to the surface of a body essentially formed ofa material selected from the group consisting of copper and its alloys,which process comprises contacting the surface of said body with astable bath consisting essentially of an aqueous solution of a nickelsalt and a hypophosphite and a stabilizer for said bath and a quantityof wear-resisting particles, and wherein said particles are nonmetallicand esentially insoluble in the plating bath and are noncata lytic andinert with respect to the reduction of the nickel salt by thehypophosphite, said particles being present in said bath in an amount byweight in the range from about 0.1 percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofnickel in said bath expressed as nickel metal, and maintaining saidparticles in suspension throughout said bath during the metallizing ofsaid body for a time sufficient to produce a coating having a thicknessof at least about 5 microns, thereby to produce an the surface of saidbody a coating of nickel having said particles uniformly dispersedtherethrough.

31. A process of coating the surface of a body with a cobalt coatingincorporating therein wear-resisting particles, which process comprisescontacting the surface of said body with a stable bath consistingessentially of an aqueous solution of a cobalt salt and a reducing agenttherefor and a stabilizer for said bath and a quantity of wear-resistingparticles, wherein said particles are nonmetallic and essentiallyinsoluble in the plating bath and are noncatalytic and inert withrespect thereto, said particles being present in said bath in an amountby weight in the range from about 0.1 percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofthe cobalt in said bath expressed as cobalt metal, and maintaining saidarticles in suspension throughout said bath during the coating of saidbody for a time sufficient to produce a coating having a thickness of atleast from 5 microns thereby to produce on the surface of said body acoating of cobalt having said particles uniformly dispersedtherethrough.

32. The process of coating set forth in claim 30, and further comprisingthe step of heating said coating to an elevated temperature for asufficient period of time to heat-harden said coating.

33. A process of coating the surface of a body with a nickelcobalt alloyincorporating therein wear-resisting particles, which process comprisescontacting the surface of said body with a stable bath consistingessentially of an aqueous solution of nickel salt and cobalt salt and areducing agent therefor and a stabilizer for said bath and a quantity ofwear-resisting particles, wherein said particles are nonmetallic andessentially insoluble in the plating bath and are noncatalytic and inertwith respect thereto, said particles,

34. The process of coating set forth in claim 33, and further comprisingthe step of heating said coating to an elevated temperature for asufficient period of time to heat-harden said coating.

35. The process of coating said coating set forth in claim 34, whereinsaid coating is heated is the approximate range C. to 600 C. throughouta time interval of at least about 1 hour.

36. A process of coating the surface of a body with a copperincorporating therein wear-resisting particles, which process comprisescontacting the surface of said body with a stable bath consistingessentially of an aqueous solution of a copper salt and a reducing agenttherefor and a stabilizer for said bath and a quantity of wear-resistingparticles, wherein said particles are nonmetallic and essentiallyinsoluble in the plating bath and are noncatalytic and inert withrespect thereto, said particles being present in said bath in an amountby weight in the range from about 0.1 percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofthe copper in said bath expressed as copper metal, and maintaining saidparticles in suspension throughout said bath during the coating of saidbody for a time sufl'rcient to produce a coating having a thickness ofat least about 5 microns, thereby to produce on the surface of said bodya coating of copper having said particles uniformly dispersedtherethrough.

37. The process of coating set forth in claim 36, wherein said reducingagent is formaldehyde.

Column Column Column Column Column Column Column Column Column PatentNo.

Dated November 2, 1971 Inventor(s) Willy Metzger; Rudi Ott; GunterPappe; Helmut Schmidt,

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Claim 11,

Claim 17,

Claim 21,

Claim 22,

Claim 29,

-- essenti are non reduction of the nickel salt by the hypophosphite,

said pa Claim Claim Claim 31,

Claim 33,

insert weight in the solids four times the cobalt and cobalt suspensionof said bo coating ha microns, w body a (:09.

line 9, "4" should be ll line 48, "slats" should be salts line 63,"slats" should be salts line 69, "0.06" should be 0.60

line 61, after "and" insert ally insoluble in the plating bath andcatalytic and inert with respect to the rticles "an" should be on line29, "articles" should be particlesline 31, after "least" insert aboutline 9, after "particles" omit comma and being present in said bath inan amount by the range from about 0.1% to about 2% of in said bath andno greater than about the combined weight of the nickel and in said bathexpressed as nickel metal metal, and maintaining said particles inthroughout said bath during the coating dy for a time sufficient toproduce a ving a thickness of at least about 5 hereby to produce on thesurface of said line 14,

ting of a nickel cobalt alloy having said RM 0-1050 UO-GS) Please turnto Page 2 USCOMM-DC 5037 fi-F'GQ 9 U 5 GOVERNMENT PRINYING OFFICE: I959O-366 334 patent 3,617,363 Dated November 2, 1971 Inventor s WillyMetzger; Rudi Ott; Gunter Pappe; Helmut Schmidt It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

(continued from Page 1) vparticles uniformly dispersed therethrough.

Column 16, Claim 35, line 14, delete "said coating".

Column 16, Claim 35, line 15, "is" should be in Column 16, Claim 36,line 18, after "copper" insert coating Signed and sealed this 13th dayof June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

2. The process of electroless metallizing set forth in claim 1, whereinsaid wear-resisting particles are silicon carbide particles.
 3. Theprocess of electroless metallizing set forth in claim 1, wherein saidwear-resisting particles are tungsten carbide particles.
 4. The processof electroless metallizing set forth in claim 1, wherein saidwear-resisting particles are molybdenum sulfide particles.
 4. Theprocess of electroless metallizing set forth in claim 1, wherein saidparticles are maintained in suspension by streams of minute bubbles ofgases passing through said bath.
 5. The process of electrolessmetallizing set forth in claim 1, wherein said wear-resisting particlesare silica particles.
 6. The process of electroless metallizing setforth in claim 1, wherein said wear-resisting particles are aluminumoxide particles.
 7. The process of electroless metallizing set forth inclaim 1, wherein said wear-resisting particles have dimensions in therange from about 0.01 micron to about 100 microns.
 8. The process ofelectroless metallizing set forth in claim 1, wherein saidwear-resisting particles have dimensions in the range from about 0.5micron to about 25 microns.
 9. The process of electroless metallizingset forth in claim 1, wherein said particles are maintained insuspension throughout said bath by mechanically agitating said bath andsaid particles.
 10. The process of electroless metallizing set forth inclaim 1, wherein said particles are maintained in suspension throughoutsaid bath by passing said bath with said particles therein past saidbody.
 12. The process of electroless metallizing set forth in claim 1,wherein said particles are maintained in suspension throughout said bathby agitation of said body within said bath.
 13. The process ofelectroless metallizing set forth in claim 1, and further comprising thestep of heating said coating to an elevated temperature for a sufficientperiod of time to heat-harden said coating.
 14. A process for coatingthe surface of a body with a nickel coating incorporating thereinwear-resisting particles, which process comprises contacting the surfaceof said body with a stable bath consisting essentially of an aqueoussolution of nickel salt and a reducing agent therefor and a stabilizerfor said bath and a quantity of wear-resisting particles, wherein saidparticles are nonmetallic and essentially insoluble in the plating bathand are noncatalytic and inert with respect thereto, said particlesbeing present in said bath in an amount by weight in the range fromabout 0.1 percent to about 2 percent of the solids in said bath and nogreater than about 4 times the weight of nickel in said bath expressedas nickel metal, and maintaining said particles in suspension throughoutsaid bath during the coating of said body for a time sufficient toproduce a coating having a thickness of at least abOut 5 microns,thereby to produce on the surface of said body a coating of nickelhaving said particles uniformly dispersed therethrough.
 15. The processof coating set forth in claim 14, wherein said reducing agent is ahypophosphite.
 16. The process of coating set forth in claim 15, whereinthe absolute concentration of hypophosphite in said bath expressed inmole/liter is within the range 0.15 to 1.20, and the ratio betweennickel and hypophosphite in said bath expressed in molar concentrationsis within the range 0.25 to 1.60.
 17. The process of coating set forthin claim 15, wherein said bath also includes a complexing agent selectedfrom the group consisting of lactic acid and slats thereof.
 18. Theprocess of coating set forth in claim 17, wherein the absoluteconcentration of lactic ions in said bath expressed mole/liter is withinthe range 0.25 to 0.60.
 19. The process of coating set forth in claim15, wherein said bath also includes an exalting additive selected fromthe group consisting of simple short chain saturated aliphaticmonocarboxylic acids including three to five carbon atoms and saltsthereof.
 20. The process of coating set forth in claim 19, wherein theabsolute concentration of said exalting additive in said bath expressedin mole/liter is within the range 0.025 to 0.060.
 21. The process ofcoating set forth in claim 15, wherein said bath also includes acomplexing agent selected from the group consisting of lactic acid andslats thereof, and an exalting additive selected from the groupconsisting of simple short chain saturated aliphatic monocarboxylicacids including three to five carbon atoms and salts thereof.
 22. Theprocess of coating set forth in claim 21, wherein the absoluteconcentration of lactic ions in said bath expressed in mole/liter iswithin the range 0.25 to 0.06, and the absolute concentration of saidexalting additive in said bath expressed in mole/liter is within therange 0.025 to 0.060.
 23. The process of coating set forth in claim 15,and further comprising the step of heating said coating to an elevatedtemperature for a sufficient period of time to heat-harden said coating.24. The process of coating set forth in claim 23, wherein the coating isheated to a temperature in the approximate range 100* C. to 600* C.throughout a time interval of at least about 1 hour.
 25. The process ofcoating set forth in claim 14, wherein said reducing agent is analkyl-borazane.
 26. A process of applying a nickel coating incorporatingtherein wear-resisting particles to the surface of a body essentiallyformed of a material selected from the group consisting of aluminum andits alloys, which process comprises contacting the surface of said bodywith a stable bath consisting essentially of an aqueous solution of anickel salt and a hypophosphite and a stabilizer for said bath and aquantity of wear-resisting particles and wherein said particles arenonmetallic and essentially insoluble in the plating bath and arenoncatalytic and inert with respect to the reduction of the nickel saltby the hypophosphite, said particles being present in said bath in anamount by weight in the range from about 0.1 percent to about 2 percentof the solids in said bath and no greater than about four times theweight of nickel in said bath expressed as nickel metal, and maintainingsaid particles in suspension throughout said bath during the metallizingof said body for a time sufficient to produce a coating having athickness of at least about 5 microns thereby to produce on the surfaceof said body a coating of nickel having said particles uniformlydispersed therethrough.
 27. The process of coating as set forth in claim26, wherein said bath additionally consists essentially of a fluoride,wherein the absolute concentration of fluoride anions in said bathexpressed in mole/liter is in the range froM about 0.001 to about 0.04.28. A process of applying a nickel coating incorporating thereinwear-resisting particles to the surface of a body essentially formed ofa material selected from the group consisting of magnesium and itsalloys, which process comprises contacting the surface of said body witha stable bath consisting essentially of an aqueous solution of a nickelsalt and a hypophosphite and a stabilizer for said bath and a quantityof wear-resisting particles, and wherein said particles are nonmetallicand essentially insoluble in the plating bath and are noncatalytic andinert with respect to the reduction of the nickel salt by thehypophosphite, said particles being present in said bath in an amount byweight in the range from about 0.1 percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofnickel in said bath expressed as nickel metal, and maintaining saidparticles in suspension throughout said bath during the metallizing ofsaid body, for a time sufficient to produce a coating having a thicknessof at least about 5 microns, thereby to produce on the surface of saidbody a coating of nickel having said particles uniformly dispersedtherethrough.
 29. A process of applying a nickel coating incorporatingtherein wear-resisting particles to the surface of a body essentiallyformed of a material selected from the group consisting of beryllium andits alloys, which process comprises contacting the surface of said bodywith a stable bath consisting essentially of an aqueous solution of anickel salt and a hypophosphite and a stabilizer for said bath and aquantity of wear-resisting particles, and wherein said particles arenonmetallic and being present in said bath in an amount by weight in therange from about 0.1 percent to about 2 percent of the solids in saidbath and no greater than about 4 times the combined weight of the nickeland the cobalt in said bath expressed as nickel metal and cobalt metal,and maintaining said particles in suspension throughout said bath duringhe coating of said body for a time sufficient to produce a coatinghaving a thickness of at least about 5 microns, whereby to produce onthe surface of said body a coating of a nickel-cobalt alloy having saidparticles uniformly dispersed therethrough.
 30. A process of applying anickel coating incorporating therein wear-resisting particles to thesurface of a body essentially formed of a material selected from thegroup consisting of copper and its alloys, which process comprisescontacting the surface of said body with a stable bath consistingessentially of an aqueous solution of a nickel salt and a hypophosphiteand a stabilizer for said bath and a quantity of wear-resistingparticles, and wherein said particles are nonmetallic and essentiallyinsoluble in the plating bath and are noncatalytic and inert withrespect to the reduction of the nickel salt by the hypophosphite, saidparticles being present in said bath in an amount by weight in the rangefrom about 0.1 percent to about 2 percent of the solids in said bath andno greater than about four times the weight of nickel in said bathexpressed as nickel metal, and maintaining said particles in suspensionthroughout said bath during the metallizing of said body for a timesufficient to produce a coating having a thickness of at least about 5microns, thereby to produce an the surface of said body a coating ofnickel having said particles uniformly dispersed therethrough.
 31. Aprocess of coating the surface of a body with a cobalt coatingincorporating therein wear-resisting particles, which process comprisescontacting the surface of said body with a stable bath consistingessentially of an aqueous solution of a cobalt salt and a reducing agenttherefor and a stabilizer for said bath and a quantity of wear-resistingparticles, wherein said particles are nonmetallic and essentiallyinsoluble in the plating bath and are noncatalytic and inert withrespect thereto, said particles being present in said bath in an amountby weight in the range from about 0.1 percent to about 2 percent of thesolids in said bath and no greater than about four times the weight ofthe cobalt in said bath expressed as cobalt metal, and maintaining saidarticles in suspension throughout said bath during the coating of saidbody for a time sufficient to produce a coating having a thickness of atleast from 5 microns, thereby to produce on the surface of said body acoating of cobalt having said particles uniformly dispersedtherethrough.
 32. The process of coating set forth in claim 30, andfurther comprising the step of heating said coating to an elevatedtemperature for a sufficient period of time to heat-harden said coating.33. A process of coating the surface of a body with a nickel-cobaltalloy incorporating therein wear-resisting particles, which processcomprises contacting the surface of said body with a stable bathconsisting essentially of an aqueous solution of nickel salt and cobaltsalt and a reducing agent therefor and a stabilizer for said bath and aquantity of wear-resisting particles, wherein said particles arenonmetallic and essentially insoluble in the plating bath and arenoncatalytic and inert with respect thereto, said particles,
 34. Theprocess of coating set forth in claim 33, and further comprising thestep of heating said coating to an elevated temperature for a sufficientperiod of time to heat-harden said coating.
 35. The process of coatingsaid coating set forth in claim 34, wherein said coating is heated isthe approximate range 100* C. to 600* C. throughout a time interval ofat least about 1 hour.
 36. A process of coating the surface of a bodywith a copper incorporating therein wear-resisting particles, whichprocess comprises contacting the surface of said body with a stable bathconsisting essentially of an aqueous solution of a copper salt and areducing agent therefor and a stabilizer for said bath and a quantity ofwear-resisting particles, wherein said particles are nonmetallic andessentially insoluble in the plating bath and are noncatalytic and inertwith respect thereto, said particles being present in said bath in anamount by weight in the range from about 0.1 percent to about 2 percentof the solids in said bath and no greater than about four times theweight of the copper in said bath expressed as copper metal, andmaintaining said particles in suspension throughout said bath during thecoating of said body for a time sufficient to produce a coating having athickness of at least about 5 microns, thereby to produce on the surfaceof said body a coating of copper having said particles uniformlydispersed therethrough.
 37. The process of coating set forth in claim36, wherein said reducing agent is formaldehyde.